It is known in the air ventilating and cleaning art for exhaust systems for cooking equipment to provide exhaust hoods, and for filtering smoke, grease, odors and other pollutants from the air exhausted through such a system. Heretofore, air curtains have been provided above the cooking equipment in a restaurant. U.S. Pat. No. 4,134,394 discloses an air ventilation system for a restaurant cooking equipment exhaust hood, and which employs tempered air drawn from the dining room of a restaurant. A disadvantage of the air ventilating system disclosed in U.S. Pat. No. 4,134,394 is that it removes air-conditioned air from the restaurant building during the cooling season, and an uncontrolled amount of heated air from the restaurant building during the heating season, and the chef cannot control the temperature of the air curtain. U.S. Pat. No. 3,800,689 also discloses a building ventilating system disposed over a cooking unit, and it provides an air curtain above the cooking unit that comprises a mixture of filtered exhaust air and fresh air. A disadvantage of the air ventilation system disclosed in U.S. Pat. No. 3,800,689 is that the air curtain includes exhausted air which may include some pollutants not filtered by the exhaust hood filtering system. U.S. Pat. No. 3,837,269 discloses an apparatus for ventilating kitchen exhaust fumes and treating the exhaust fumes to remove air pollutants, and then exhausting the fumes to the atmosphere, or partially recirculating some of it through the kitchen cooking area. The last described air ventilating system does not provide any air curtain for the comfort of the chef working with the cooking equipment which is ventilated by the air system of the last mentioned patent.
U.S. Pat. No. 3,978,777 discloses a ventilating apparatus for restaurant cooking equipment in which part of the make-up air entering the exhaust hood of the ventilating apparatus is untempered air, and a portion of the air entering the exhaust hood is tempered air drawn from the surrounding room. A disadvantage of the ventilating apparatus shown in the last mentioned patent is that there is no control over the supply source of the tempered air which is under the exhaust hood and it is all drawn from the kitchen area surrounding the cooking equipment. U.S. Pat. No. 3,457,850 discloses an air ventilation system for cooking equipment which uses untempered or fresh air for the make-up air to replace the exhaust gases. It also employs the use of an outlet register in the make-up air supply system to permit some of the untempered air to be blown into the kitchen in a position over the head of the chef operating cooking equipment but not directly downward. The flow of untempered air is directed outwardly into the surrounding room area. The temperature of the untempered air entering the room in accordance with the last described air ventilation system would depend on the outside air temperature, and an outside air blower is provided with a cooler which could be used on warm days to provide cool make-up air.
U.S. Pat. No. 3,890,887 discloses an air ventilation system for restaurant cooking equipment which employs temperature controlled fresh air for make-up air, and for directing a portion of the same into the kitchen area around the cooking equipment. A disadvantage of the air ventilation systems shown in the last two mentioned patents is that they require a separate cooling means in their fresh air supply circuit, which increases the energy requirements for operating the air ventilation system.
U.S. Pat. No. 3,411,428 discloses a ventilating hood for cooking equipment in which the make-up air is supplied from the exterior of the building, and wherein the make-up air may be supplied by outside air which can be heated before it is conveyed under the exhaust hood. The air ventilating system disclosed in the last mentioned patent does not provide any controllable air curtain for the chef operating the cooking equipment. U.S. Pat. No. 3,980,072 discloses a cooking equipment ventilating system which employs all untempered or outside air for make-up and air curtain purposes.
U.S. Pat. No. 3,664,255 discloses an air ventilation system, for restaurant cooking equipment, in which all of the make-up air is supplied from the exterior of the room in which the cooking equipment is located. A disadvantage of the air ventilating structure disclosed in the last mentioned patent is the fact that it does not provide any comfort air curtain for the chef operating the cooking equipment.